Multi-antenna configuration signaling in wireless communication system

ABSTRACT

A wireless communication infrastructure entity ( 200 ) having a communication configuration is configured to generate parity bits based on an information word and to encode the parity bits based on the communication configuration of the wireless communication infrastructure entity, wherein the encoded parity bits are combined with the information word. A wireless communication user terminal is configured to identify a set of configuration indicator bits used to encode parity bits combined with an information word and to determine a communication configuration of the wireless communication entity from which the combination of the information word and the encoded parity bits were received based on the set of configuration indicator bits used to encode the parity bits.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications andmore particularly to multi-antenna configuration signaling in wirelesscommunication systems.

BACKGROUND

In 3GPP, the Long Term Evolution (LTE) of Universal MobileTelecommunications Systems (UMTS) is expected to permit up to 4 antennaports to be defined for multi-antenna base station transmissions andpermits using 1, 2 or 4 antenna ports for selected physical channeltransmissions. The Physical Broadcast Channel (PBCH) may be transmittedusing all three of these latter antenna port configurations. Since thebase station does not explicitly signal the antenna configuration viathe synchronization channel, the user equipment (UE) is required todecode the PBCH without the assistance of base station antennaconfiguration information acquired during an earlier phase of theinitial network access procedure. In particular, the PBCH-borne MasterInformation Block is transmitted as a convolutionally encoded codewordwith an inner cyclic redundancy check (CRC), but it is possible even athigh signal-to-noise ratios for the UE to fail to identify the number ofantennas present solely by inspection of the common reference symbols(RS). Similarly, it is possible for the UE to incorrectly identify thebase station antenna configuration when hypothesis-testing the transmitdiversity scheme associated with each permitted antenna configuration incombination with a PBCH CRC testing. For example, when transmittingusing the specified 2 antenna transmit diversity scheme ofspace-frequency block coding (SFBC), a UE can correctly decode the PBCHcodeword when hypothesizing (incorrectly) 1 antenna transmission.

3GPP R1-073970 discloses several possible approaches to communicatingbase station antenna configuration information for corresponding PBCHtransmissions. In one approach, the mapping of PBCH codeword to OFDMsymbols and sub-carriers (i.e. resource elements) is changed accordingto the multi-antenna configuration. 3GPP R1-074861 suggests, however,that the mapping of the PBCH codeword onto resource elements should notvary with the antenna configuration. According to a second approach, thePBCH codeword is scrambled with different scrambling sequences, whereinthe sequence is conditioned on the base station antenna configuration.This approach require the UE to de-scramble the log-likelihood ratios(LLRs) arising from each hypothesized multi-antenna configuration priorto attempting convolutional decoding and CRC checking. In this secondapproach, one descrambling operation is required for each antennaconfiguration hypothesis. A third approach requires changing theAlamouti code (SFBC or SFBC+FSTD) according to the antennaconfiguration. This would require the UE to support more transmitdiversity mapping configurations. Accordingly, some further, lowcomplexity means of assisting the UE in discriminating the antennaconfiguration is needed.

The various aspects, features and advantages of the disclosure willbecome more fully apparent to those having ordinary skill in the artupon a careful consideration of the following Detailed Descriptionthereof with the accompanying drawings described below. The drawings mayhave been simplified for clarity and are not necessarily drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system.

FIG. 2 is a wireless communication infrastructure entity block diagram.

FIG. 3 is a wireless communication infrastructure entity process flowdiagram.

FIG. 4 is a wireless communication user terminal block diagram.

FIG. 5 is a wireless communication user terminal process flow diagram.

DETAILED DESCRIPTION

In FIG. 1, a wireless communication system 100 comprises one or morefixed base infrastructure units forming a network distributed over ageographical region. The base unit may also be referred to as an accesspoint, access terminal, base, base station, Node-B, eNode-B or by otherterminology used in the art. In FIG. 1, the one or more base units 101and 102 serve a number of remote units 103 and 110 within a servingarea, for example, a cell or a cell sector. The remote units may befixed units or mobile terminals. The remote units may also be referredto as subscriber units, mobiles, mobile stations, users, terminals,subscriber stations, user equipment (UE), terminals, or by otherterminology used in the art.

Generally, the base units 101 and 102 transmit downlink communicationsignals 104 and 105 to serve remote units in the time and/or frequencydomain. The remote units 103 and 110 communicate with the one or morebase units via uplink communication signals 106 and 113. The one or morebase units may comprise one or more transmitters and one or morereceivers for downlink and uplink transmissions. The remote units mayalso comprise one or more transmitters and one or more receivers.

In one implementation, the wireless communication system is compliantwith the developing Long Term Evolution (LTE) of the 3GPP UniversalMobile Telecommunications System (UMTS) protocol wherein the basestation transmits using an orthogonal frequency division multiplexing(OFDM) modulation scheme on the downlink and the user terminals transmiton the uplink using a single carrier frequency division multiple access(SC-FDMA) scheme. More generally, however, the wireless communicationsystem may implement some other open or proprietary communicationprotocol. The present disclosure is not intended to be limited to theimplementation of any particular wireless communication systemarchitecture or protocol.

In some systems, each base station, and more generally some otherwireless communication infrastructure entity, has a communicationconfiguration. In one embodiment, the communication configuration is anantenna configuration of the base station. In 3GPP, for example, theLong Term Evolution (LTE) of Universal Mobile Telecommunications Systems(UMTS) is expected to permit up to 4 antenna ports to be defined formulti-antenna base station transmissions and permits using 1, 2 or 4antenna ports for selected physical channel transmissions. The PhysicalBroadcast Channel (PBCH) may be transmitted using all three of theselatter antenna port configurations. Thus the multiple base stations thatconstitute a wireless communication system may potentially havedifferent antenna configurations. Also, in some system implementations,the antenna configuration of the one or more base terminals is changeddynamically.

In 3GPP, currently, the UE is required to decode the PBCH without theassistance of base station antenna configuration information acquiredduring an earlier phase of the initial network access procedure sincethe base station does not explicitly signal the antenna configurationvia the synchronization channel. Accordingly, a means for assisting theUE in discriminating the antenna configuration of the base station isdesired in some instances, particularly where neighboring base stationshave different configuration and/or where the antenna configuration ofthe base station dynamically. There may also be instances where it isdesirable for the base station to signal the transmit antennaconfiguration that should be adopted by the terminal.

The present disclosure is not intended to be limited to communicating orassisting a user terminal with the determination of the antennaconfiguration of a particular base unit. More generally, the wirelesscommunication infrastructure entity may assist one or more entities withthe determination of communication configuration of the wirelesscommunication infrastructure entity or with the determination of thecommunication configuration of or for the wireless communicationterminal. For example, the communication configuration information maybe in the form of any one or more of the following: the antennaconfiguration of the wireless communication terminal; information oncell identity information (this can sometimes be transferred byassociation with e.g. a synchronization channel identifier); informationconcerning the duration of frame or slot structure; the configuration ofthe cell as a paired (e.g. frequency-division duplexing, FDD) orunpaired (e.g. time-division duplexing, TDD) transmission; symmetric orasymmetric downlink and uplink frequency resources; the type and/ornumber of transmitted pilot or reference symbols; whether broadcast orunicast service is supported; the presence of superposed channeltransmissions; admission control data; the association of adjacent ornon-adjacent spectrum; the number of accessible carriers or carrierrelationships in case of a multi-carrier structure; the cell and carriertype and relationship to other cells in a hierarchical cell structure ormulti-carrier hierarchical cell structure; a dedicated broadcast carrierin an SFN; among other information.

In FIG. 2, a wireless communication infrastructure entity 200 having acommunication configuration comprises a transceiver 210 communicablycoupled a controller 220. In one embodiment, the wireless communicationinfrastructure entity corresponds to one of the base units of FIG. 1wherein the communication configuration is an antenna configuration. Thetransceiver generally communicates with one or more user terminalswithin its coverage area. In FIG. 2, the controller is most readilyimplemented as a digital processor controlled by software and/orfirmware stored in memory 230. Alternatively however the controller maybe implemented as a hardware equivalent device or as a combination ofhardware and software. The controller includes parity bit generationfunctionality 222 used to generate parity bits based on an informationword that is to be transmitted to a user terminal. Thus under softwareand/or firmware control, the controller is configured to generate paritybits based on an information word. In the process flow diagram 300 ofFIG. 3, at 310, the wireless communication network infrastructure entitygenerate parity bits, for example, Cyclic Redundancy Check (CRC) bitsbased on an information word, for example a transport block. In FIG. 2,at 223, the parity bits are combined with the information word.

In FIG. 2, the controller includes parity bit encoding functionality 224used to encode communication configuration information of the wirelesscommunication infrastructure entity on the parity bits. The controlleris configured to encode the parity bits based on the communicationconfiguration of the wireless communication infrastructure entity undersoftware and/or firmware control. In other embodiments, more generally,other communication configuration information could be encoded on to theparity bits. In one embodiment, the controller is configured to encodethe parity bits by masking the parity bits with a unique set ofconfiguration indicator bits corresponding to the communicationconfiguration of the wireless communication infrastructure entity. Inone implementation, the masking may be performed by XOR-ing the paritybits with the set of configuration indicator bits. The mask could begenerated by, for example, selecting 3 length-N masking words where N isthe PBCH CRC parity field length (and is likely 16 bits) with maximumHamming distance. Such a set of masking words could include, forexample, the all-zero or null masking word corresponding to the 1antenna configuration without loss of generality. By extending thenumber of states and therefore the number of applicable masks, anyfurther information relating to the base station antenna configurationcould also be encoded.

The mask or parity field modifier could also be conditioned on the basestation physical cell ID, or the duration of a frame or slot structure,or the configuration of the cell as a paired (e.g. frequency-divisionduplexing, FDD) or unpaired (e.g. time-division duplexing, TDD)transmission, symmetric or asymmetric downlink and uplink frequencyresources, the type and number of transmitted pilot or referencesymbols, the type of service supported (e.g. broadcast, unicast), thepresence of superposed channel transmissions, admission control data,the association of adjacent or non-adjacent spectrum, the number ofaccessible carriers or carrier relationships in case of a multi-carrierstructure, the cell and carrier type and relationship to other cells ina hierarchical cell structure or multi-carrier hierarchical cellstructure; among other communication configuration information, someexamples of which are discussed above.

The information word is generally combined or otherwise associated withthe encoded parity bits before transmission to the user terminal. In oneembodiment, the controller is configured to combine the information wordand the parity bits by concatenating the parity bits to the informationword, for example, at the beginning or end thereof, before or after theparity bits are encoded. Alternatively, the parity bits may be insertedinto a mid portion of information word or the parity bit may beinterleaved with the information word before or after encoding.

In FIG. 3, at block 320, the wireless communication infrastructureentity combines the information word and the parity bits and then at 330encodes the parity bits based on the communication configuration of thewireless communication infrastructure entity. In an alternativeembodiment, the parity bits are first encoded and then combined with theinformation word. Thus in FIG. 2, the spatial location of the ordercombining functionality is not necessarily indicative of order in whichit occurs relative to the parity bit encoding function. In someembodiments, in FIG. 2, the controller includes channel codingfunctionality used to channel code the information word and the combinedencoded parity bits before transmitting. In FIG. 3, at 340, theinformation word combined with the encoded parity bits are channel codedbefore transmission at 350. In FIG. 2, the controller communicates thechannel coded information word and parity bits to the transceiver fortransmission.

In FIG. 4, a wireless communication user terminal 400 comprises atransceiver 410 communicably coupled a controller 420. In oneembodiment, the user terminal corresponds to one of the remote units ofFIG. 1. The transceiver generally communicates with one or more baseunits. In FIG. 4, the controller is most readily implemented as adigital processor controlled by software and/or firmware stored inmemory 430. Alternatively however the controller may be implemented as ahardware equivalent device or as a combination of hardware and software.In the process flow diagram 500 of FIG. 5, at 510, the user terminalreceives an information word combined with encoded parity bits from awireless communication entity.

In FIG. 4, the controller includes functionality 422 used to identify aset of configuration indicator bits used to encode parity bits that arecombined with an information word. In FIG. 4, the controller alsoincludes functionality 424 used to determine a communicationconfiguration based on the set of configuration indicator bits used toencode the parity bits. In one embodiment, the controller is configuredto determine a communication configuration of the wireless communicationentity from which the combination of the information word and theencoded parity bits were received based on the set of configurationindicator bits used to encode the parity bits. In another embodiment,the controller is configured to determine a communication configurationof the wireless communication user terminal based on the set ofconfiguration indicator bits used to encode the parity bits.

In one implementation illustrated in FIG. 5, at 520, the user terminalrecovers the parity bits from the encoded parity bits. In oneembodiment, the parity bits are recovered by XOR-ing the encoded paritybits with a set of configuration indicator bits. At 530, the userterminal performs error detection on information word using therecovered parity bits. In one embodiment, the user terminal performs theXOR-ing process for each possible set of configuration indicator bits,wherein the set of configuration indicator bits indicative of thecommunication configuration of the wireless communication entitycorresponds to the set of configuration indicator bits for which thedetected errors in the information word is relatively low. For example,the errors detected may be zero or at least less than the detected errorassociated with the other configuration indicator bits. Thecommunication configuration of the wireless communication entity isindicated by not more than one set of configuration indicator bits.

While the present disclosure and the best modes thereof have beendescribed in a manner establishing possession and enabling those ofordinary skill to make and use the same, it will be understood andappreciated that there are equivalents to the exemplary embodimentsdisclosed herein and that modifications and variations may be madethereto without departing from the scope and spirit of the inventions,which are to be limited not by the exemplary embodiments but by theappended claims.

1. A wireless communication infrastructure entity having a communicationconfiguration, the entity comprising: a transceiver; a controllercommunicably coupled to the transceiver, the controller configured togenerate parity bits based on an information word, the controllerconfigured to encode the parity bits based on the communicationconfiguration of the wireless communication infrastructure entity, theencoded parity bits combined with the information word.
 2. The entity ofclaim 1, the controller configured to encode the parity bits by maskingthe parity bits with a unique set of configuration indicator bitscorresponding to the communication configuration of the wirelesscommunication infrastructure entity.
 3. The entity of claim 2, thecontroller configured to perform the masking by XOR-ing the parity bitswith the set of configuration indicator bits.
 4. The entity of claim 1,the wireless communication infrastructure entity is a base station andthe communication configuration is an antenna configuration, thecontroller configured to encode the parity bits by masking the paritybits with a set of configuration indicator bits indicative of theantenna configuration of the wireless communication infrastructureentity.
 5. The entity of claim 4, the controller configured to performthe masking by XOR-ing the parity bits with the set of configurationindicator bits.
 6. The entity of claim 1, the controller configured tocombine the information word and the parity bits by appending the paritybits to the information word before encoding the parity bits.
 7. Theentity of claim 1, the controller configured to channel code thecombined information word and encoded parity bits before the channelcoded information word and encoded parity bits are transmitted.
 8. Theentity of claim 1, the controller configured to combine the parity bitwith the information word, and to encode the parity bits based on thecommunication configuration of the wireless communication infrastructureentity after combining.
 9. The entity of claim 8, the wirelesscommunication infrastructure entity is a base station and thecommunication configuration is an antenna configuration, the controllerconfigured to encode the parity bits by XOR-ing the parity bits with aset of configuration indicator bits indicative of the antennaconfiguration of the wireless communication infrastructure entity. 10.The entity of claim 1, dynamically configuring a new communicationconfiguration, the controller configured to encode parity bits based onthe new communication configuration of the wireless communicationinfrastructure entity.
 11. A method executing in a wirelesscommunication infrastructure entity having a communicationconfiguration, the method comprising: generating parity bits based on aninformation word; combining the information word and the parity bits;encoding the parity bits based on the communication configuration of thewireless communication infrastructure entity; and transmitting theinformation word and the encoded parity bits.
 12. The method of claim11, encoding the parity bits by XOR-ing the parity bits with a set ofconfiguration indicator bits corresponding to the communicationconfiguration of the wireless communication infrastructure entity. 13.The method of claim 11, the communication configuration is an antennaconfiguration, encoding the parity bits by XOR-ing the parity bits witha set of configuration indicator bits indicative of the antennaconfiguration of the wireless communication infrastructure entity. 14.The method of claim 13, channel coding the combined information word andencoded parity bits, and transmitting the channel coded information wordand encoded parity bits after channel encoding.
 15. The method of claim11, combining the information word and the parity bits by concatenatingthe parity bits and the information word.
 16. A wireless communicationuser terminal, comprising: a transceiver; a controller communicablycoupled to the transceiver, the controller configured to identify a setof configuration indicator bits used to encode parity bits that arecombined with an information word, wherein the encoded parity bitscombined with the information word are received by the transceiver froma wireless communication entity before the controller identifies the setof configuration bits, the controller configured to determine acommunication configuration based on the set of configuration indicatorbits used to encode the parity bits.
 17. The terminal of claim 16, thecontroller configured to recover parity bits from the encoded paritybits by XOR-ing the encoded parity bits with the set of configurationindicator bits, the controller configured to perform error detection onthe information word using the parity bits after recovering, wherein theset of configuration indicator bits are indicative of the communicationconfiguration if detected errors in the information word is relativelylow.
 18. The terminal of claim 16, the controller configured to recoverthe parity bits from the encoded parity bits by XOR-ing the encodedparity bits with each of at least two different sets of configurationindicator bits to generate corresponding sets of parity bits, thecontroller configured to perform error detection on the information wordusing each set of parity bits after recovering, the set of configurationindicator bits indicative of the communication configuration correspondsto a set of configuration indicator bits used to generate a set ofparity bits for which detected errors in the information word arerelatively low, the communication configuration is indicated by not morethan one set of configuration indicator bits.
 19. The terminal of claim16, the controller configured to determine a communication configurationof the wireless communication entity from which the combination of theinformation word and the encoded parity bits were received based on theset of configuration indicator bits used to encode the parity bits. 20.The terminal of claim 16, the controller configured to determine acommunication configuration of the wireless communication user terminalbased on the set of configuration indicator bits used to encode theparity bits.